1. The Geologic Time Scale
Aim: How do we study life on Earth?

2. I. Geologic Time Scale
A chart used to study changes on the Earth over the past 4.6 billion years of existence.

3. Geologic Time Scale Continued…
A. A geological time can be studied accurately by splitting it up into units from bigger time spans to smaller ones in the followings ways:
EONS  ERAS  PERIODS  EPOCHS
(largest) (smallest)
B. The geologic time scale is also useful for studying evolution of life forms over time.

4. II. Theory of Natural Selection
It was proposed by Charles Darwin in The theory stated that those organisms that are better adapted to their environment will produce more offspring and thrive while those animals not well adapted to their environment will go extinct.
The story of the moths

5. Evolution of Man